Asked
how much longer she thought Assad can sustain his control, Clinton said: "I can't sit here and predict it but I think the pressure is building."

The secretary of state also noted that she does not expect an international force to intervene in Syria the way that US and NATO forces did in Libya.

Anti-Assad protest (Photo: Reuters)

In a separate interview with ABC News, Clinton noted that Assad "is not going to be able to sustain what is a growing armed opposition apparently led and fuelled by defectors from his army."

Meanwhile, the Wall Street Journal on Friday reported that the United States and its European allies are focusing their efforts on blocking money transfers between Syria and Lebanese banks.

Assad with US Ambassador Ford (Photo: AFP)

According to the report, the White House is hopeful that the financial pressure will serve as a final blow to Assad's regime, which has been suffering due to sanctions on oil exports and the faltering tourism industry.

The US Treasury assistant secretary on illicit financing, Daniel Glaser visited Beirut recently, and warned local banks against trading with Syria, saying they risk being "blacklisted" by the United States and Europe.

Commenting on the pressure mounted by global leaders and the Arab League, Clinton said that European pressure is more effective because there is much more trade going on between Europe and Syria than between the United States and Syria.